1. The Field of the Invention
The present invention relates generally to apparatus and methods for use in the collection of a Pap smear. More particularly, the present invention provides a novel design which permits simultaneous collection of cells from the cervical face and from the endocervical canal. The device also provides a method and means for securing a vaginal sample without reverting to a second sampling device.
2. The Background of the Invention
Over the last 40 years, the death rate from cervical cancer has dropped dramatically due to the widespread use of the Papanicolaou ("Pap") test. This test involves the collection of cells from the cervical face, the endocervical canal and occasionally from the vaginal wall. These cells are then microscopically examined for evidence of precancerous or cancerous growth. The periodic use of this test permits early detection of malignancy so that palliative therapy can be initiated at a time when it will yield the highest possible success rate.
For many years the standard method for collection of these cells has been a wooden or plastic spatula. A variety of slightly different shapes have been used in an effort to allow the clinician to collect cells from the cervical face as well as the endocervical canal. In some cases, the opposite end of the spatula was designed to collect a vaginal scraping.
For the most part, these designs have been able to retrieve cells from the surface of the cervix and the vaginal wall but have frequently failed to collect adequate cell samples from the endocervical canal. This has been a serious problem because any sample which does not include endocervical cells is deemed to be inadequate for proper interpretation and diagnosis. Further, many women who have had an inadequate sample taken are reluctant to have the procedure repeated and may be placed at risk for progression of their disease until their next periodic checkup.
A delay in the diagnosis of cervical or uterine cancer can result in the need for far more radical treatment procedures than would be needed if the cancer were detected earlier. In the worst case, a delay in diagnosis could result in the progression from treatable cancer to a terminal cancer.
Recent modifications in collection procedures have added a cotton swab to the technique in an effort to collect endocervical cells. The cotton swab is inserted into the cervical canal and rotated. Although the cotton swab may somewhat improve the yield, it is not abrasive enough to scrape the endocervical canal and consistently retrieve an adequate sample.
Another modification made in an attempt to collect endocervical cells is what is called a "cytology brush." This cytology brush has on the end of a long handle a conically-tapering brush made of spiraling bristles. When the brush is rotated within the endocervical canal, cells become entrapped by the brush. However, while the cytology brush can consistently obtain endocervical cells, the brush is too abrasive, and so its use increases the incidence of bleeding and discomfort and, in addition, adds considerable cost to a very price-sensitive procedure.
If bleeding occurs during collection, the red blood cells may obscure other cells on the cytology slide and make interpretation difficult or impossible. When this happens, the cell collection procedure must be repeated. As many "Pap smears" are performed in public health clinics and similar free or low-cost environments, the device to be used must not substantially increase the material costs of the procedure.
Another disadvantage to the cytology brush has been that entry of the brush into the endocervical canal is difficult to control. If the brush is extended too far inside the canal, injury to the endocervix may result. It is difficult for the user to determine proper penetration of the cytology brush.
Recently, some changes in the design of cytology brushes have been taking place, aimed primarily at decreasing the incidence of cervical bleeding and improving the ease with which cells are extracted from the bristles. These changes have been somewhat effective but have typically further increased the cost of the brushes.
One change has been to design a broom-like device to simultaneously collect cells from the ectocervix and endocervix. This brush has bristles which extend forward from a cross piece and looks very much like a broom. The central bristles are longer than the lateral bristles and are intended to enter the endocervical canal while the lateral bristles make contact with the ectocervix. The collection difficulties arise from the fact that the central bristles are parallel to the walls of the endocervical canal and, thus, very little abrasive effect is generated, especially if there is any dilation of the canal. As a result, endocervical cells are not consistently collected.
Further disadvantages of the prior art devices are in transferring the cells for examination. After cells have been collected, they are usually transferred to a microscopic slide for later examination. This is accomplished by wiping the collecting apparatus, whether spatula, brush swab, or broom, directly against the surface of the slide. A fixative is then applied to avoid any deterioration of the cells before the cytology technician and/or pathologist can examine them. Unfortunately, many doctors lack time and patience to transfer every collected cell from the device with a microscopic slide and so valuable diagnostic material may be lost, resulting in risk of erroneous diagnosis. With the spiral brush, it is and excess time and care to do so is necessary. In some cases, the presence of mucous or blood or the knowledge that the patient is at high risk, can make this type of slide preparation inadequate. A monocellular preparation may be requested. In this technique, the samples must be transferred from the collection device(s) into a container of fixative. The container is then centrifuged until all cellular components have collected at the bottom of the container as a "cell pellet." After the excess fixative is pipetted off, the cell pellet can be spread evenly onto a slide. This provides a slide with very little cellular overlap. Mucous will have gone into solution and any red blood cells will be sufficiently spread so as to avoid obscuring other cells.